Spatial coverage

Mapping out points where speed (brown points) and volume (green points) were measured year by year, we see that the measurement locations are quite different between years but very similar (though not identical) between speed/volume measurements in a given year.

Temporal coverage

Upshot: Measurement dates vary systematically from year to year. This includes the months covered, the share of weekdays/weekends covered, as well as the share of weekends by month.

The temporal distribution of speed data is quite similar to volume data but not exactly the same.

Coverage of data through the hours of the day is even (i.e., for each measurement instance there is one row for each hour).

Speed

Volume

Speeding descriptives

Characteristics of measurement locations

Joining the 2022-2025 speed measurement data spatially to Philadelphia street centerlines, we get this coverage:

There are a few measurement points at highways and highway ramps. We exclude them for all analyses below.

The distribution of speed measurement points by roadway type is thus:

Roadway type N Percent
Major Arterial 230.00 41.97%
Minor Arterial 166.00 30.29%
Collector 132.00 24.09%
Local 20.00 3.65%

Speeding by time of day

Overall

Binary

Detailed

By roadway type

Binary

Detailed

Off-peak speed corridors

Where are the roadways where the prevalence of speeding at off-peak hours is the highest?

Any speeding

The table below shows roadway type distribution for segments where more than half of traffic speeds in off-peak hours.

Distribution of roadway types with more than half of traffic speeding in off-peak hours
Roadway type N Percent
Major Arterial 76.00 54.68%
Minor Arterial 37.00 26.62%
Collector 24.00 17.27%
Local 2.00 1.44%
Percentage of measurement points with more than half of traffic speeding in off-peak hours, by roadway type
Roadway type Percent
Major Arterial 33.04%
Minor Arterial 22.29%
Collector 18.18%
Local 10.00%

Major arterials and high speed ramps are disproportionately prone to speeding drivers in off-peak hours.

The map below shows the location of these majority-speeding roadways.

High speeding

The table below shows roadway type distribution for segments where more than 10% of traffic speeds 11mph or more over the limit in off-peak hours.

Distribution of roadway types with more than 10% of traffic speeding by more than 11mph in off-peak hours
Roadway type N Percent
Major Arterial 53.00 66.25%
Minor Arterial 19.00 23.75%
Collector 6.00 7.50%
Local 2.00 2.50%
Percentage of measurement points with more than 10% of traffic speeding by more than 11mph in off-peak hours, by roadway type
Roadway type Percent
Major Arterial 23.04%
Minor Arterial 11.45%
Collector 4.55%
Local 10.00%

Major arterials and high speed ramps are even more disproportionately prone to high-speeding drivers in off-peak hours.

The map below shows the location of these high-speeding roadways.

Relationship between volume and speeding

Are drivers more likely to speed for a given roadway type if overall volume is lower?

Any speeding

There doesn’t seem to be any definitive pattern.

High speeding

There doesn’t seem to be any definitive pattern.